There are corrugated boxes offered by us that have rows of small air-filled grooves running the length of the material. Theyre made from paperboard and typically have three layers. The liner board is the flat, thick paper that looks smooth. Corrugated means wrinkled or furrowed. This wrinkled like layer can visibly be seen on the inside of these boxes. Unlike regular cardboard boxes that are made of heavy-duty paper stock, corrugated boxes have three different layers. The first is the outside liner, then they have the inside liner, and finally, corrugated boxes have the fluting that is in-between the two.